Manufacture of rubber articles



Aug. 7, 1934- w. 1 sEMoN MANUFACTURE OF RUBBER ARTICLES Filed April 18,1929 ENDI? Patented Aug. 7, 1934 UNITED A-s'frlil'll3s P ENT MANUFACTUREoF RUBBER'ARTICLES Waldo L. Semon, Cuyahoga Falls, Ohio, assignor to TheB. F. Goodrich Company, New York,l

N. Y., a corporation of New York Application April 1s, 1929, serial. No.'356,227 f 14 Claims.

' of -rubber or rubber articles by thetraditionalV methods greatlydegrades or even destroys the strength, elasticity and chemicalstability of the rubber, land that these properties are onlyimvperfectly restored during the vulcanization process. Y

It'has therefore been proposed to manufacture rubber varticles directlyfrom rubber latex without masticatiom depolymerization or similardestructive processes. .The vulcanizing agents, -accelerators, fillersari-dother conditioning or modifying agents are dispersed in water and.addedto the liquid latex,f. the rubber and such additional substancesbeing separated from the water simultaneously. The separation of therubber has been accomplished by electrodeposition on conducting forms,by `coagulation on porous forms impregnated'with a coagulant, and bydipping forms and drying successive thin layers thereon. Such methods,however, require very careful control ofthe properties of the latex andof the manufacturing operations and hence do not readily lend themselvesto continuous quantity production. 1

This invention consistsin manufacturing a continuous succession ofsimilar articles by pass- `ing a series of forms over-a bank of spraynozzles whichspray thereon a layer of latex of thedesired thickness. If'it' is desired to apply a heavy layer of rubber, the latex is partiallydried ydui'- ing the spraying operation, or between two suc- '-cessiveapplications, in order thatr the rubber layer as it is builtr up may beself-'supportingand free from all tendency to iiow. The coated forms arepassed through a drying chamber, in which the greaterpart of theremaining moisture is eliminated.

The invention will be'readily understood by reference to the vspecificembodiments` shown in j the accompanying drawing.

Fig. l is a side view' of `a machine for the continuous lmanufacture 'oftubes, 'such asl .inner tubesI for automobile tires, one wall ofthemachine'. being broken -away to expose the interior.

Fig. 2 is a sectional View taken through the pair of chain conveyors 11,composedof alternate plain doublevlinks-lZ; 12; which engagethe teeth ofthe drive sprockets I3 and the idler-sprockets by the 10mg arms 19 of'the bifurpated iinksns.

' oi revolution may be still furtherlincreasedby 4de- 'creasingltheaxle' dial-heter.- fThe' chainsreturn- 14, and bifurcated vsingle links15; 15,-'which-support and drive the tube mandrels 16,r 16. The Vchainsare driven at; a slow but 'uniform rate`v of rspeed by any convenientmeans, for example by power.- The mandrels 16, 16, which may -be made ofany convenientmaterial, such as aluminum, steel, Istainless iron, oreven wood, are cylindrical in shape, the length and diameterbeingfchosen 70 with reference to the size of,V tube whichisbeirigmanufactured.V 'Ihey are provided with 1 rigid axles 20, which arepreferably small in diameter the chain 17-'rom `an independent sourceVof f65 compared with'the diameter of the mandrel, say

one-tenth aslarge.v YThe Yuncoated mandrels'are C755 supported by theiraxles Vina 1loadingr ack` 21=, which is inclined toward the machineproper to permit the first mandrelgtoroll down against `'the stop 22 atthe 'endof the loading rack-'j' v The bifurcated links 15,l `15 ofv thechaincon- L80 veyor 11 are provided withy short `front armsf-18 and longback arms 19, which are rmoreV clearly' shown in the enlarged View lofFig. 3.v 'As theV chain revolves about Vthe idler sprocket `14`of Fig. A1, the short Afront arms 1,8 of the links 'clear the axles 20 of themandrels linvthe loading rack 21, Abut the llonger back'arms 19engager-the' axles and lif-t the first mandrel upoutlof the loading rackand carry it into the tunnel 10Q Thereupon the succeeding mandrel in theJloading'rack-rolls 90 down against thestop 22, and is in' its vturnpicked up by the next'bifurcated conveyor link. The conveyor chains 11,11 aref supported in y their passage through thetunnel y10 by horizon'-Vtal rails v23, 2,3,1the ,positionof vwhich, is clearly C indicated inFig. 2.v Above `these isa secondpair pf raus 24., 24,1which1ifttheimandrelfs ,16, iacff the conveyor'links 1 5 to such, a height thatthe mandrels roll along the rails Q24, 24, beingdriven ,100

Because of the small diameter of the axles A20, the mandrels' revolveseveral times about their laxes during 'their' progression forward adistance corresponding to'o'rie mandrel diameter.' For .exam-1mg ple, ifthe ratio of'mandr'el diameter to axle diameteris 10 tol, the,mandrels'jwill revolve or 3.18

times whiie they progress opefdiameter; V'1'nf.' '1cae ing" underneaththe tunnel may baksupportediif desired by U-shaped rails 251225955? Theinlet Yend ofthe tunnel i 10 in Fig. l1,is'provided Withan enlargement26Vv beneath thejconveyors ll'to accommodate abank vof sprays 2'7,v 27,

y-wlrichare supplied with latexthrough a'pipe 28 from atank 29..The'number of rows'ofsp'rays is l such-that 'the desired'thickness ofrubber is de-V posited onthemandrels during their passage over '.120

the sprays. Four rows are shown in the drawing, buteither more or fewermaybe employed. I The spraynozzles inyeach row are preferably disposedclose enough to one anotherfthat their spray cones overlap, and thenozzles of successive ...pendgonaithje composition of the-latex mixture,

i, atomizernozzlesibeing preferred f ory use with mix- ;ture.S;aWh-ichtend toiclog ordinary nozzles.

. AZgblOwer-SQ draws airgthroughan air conditionerl,Which-simultaneously heats the air and regulates its humidity, anddischarges thegheated aiytnrough-the conduit 32 into medischarge end ofV:theftunnel 10.v The air passing over the I coatedmandrels dries. themthoroughly; alare@ part of-the.dryingbeing-.accomplished during theactual spraying operation. The used airis-vented j toythe atmospherethrough -fthe conduit. 7. The=coatedmandre1sgpassoutof the tunnel-l0andapproachthe driving sprocket 13. Asthe conveyor Fig.` 3 passes overtheA sprocket, the

A mandrels.-16am `dropped-on the receiving rack ,134.. The curved .guidebar 35i serves to retain the mandrels in their positionfinthe slots ofthe bifurcated conveyorflinks V15 until they-` are immediatelyadjacentEtothe-rack 34, when the termination ofcthe barl 35'allowsthemandrelsto roll oft theconveyor and down the receiving rack to theI stop36atthe lower end .thereof Each suc- 1 cessive mandrel as itftakes itsplace depresses the lowervv end 37v of :a centrally pivoted spacing stop38,*the upper-weighted'end 39 of. which rises and stops .the next,succeeding -mandrelout of` contact-With vthe preceding onevandthereforeeliminatespossible damageto the-unvulcanized rubber.As-.eachmandrel is removedfrom` theraek, it releasesfthe-spacingstop38,` theheavyend 39-drop ping` back belovvthe level of the rails ofthe-receivingraekf and permittinggthe `succeeding,man-

drel .torol-l .down and .takeits place.

The operation Iof the. machine is preferably so regulatedI that thelatex is Ydeposited -on themandrelsin numerous thin .,layers, each ofwhich `is partially `dried by the current'of heated air passlingY over;the rotating'Y mandrelsv before the succeeding'layer is applied. Thedrying of,r each layerh-should'be justsuiiieient to renderthe rubhigh;tof `.preventfthe formation pf, a. {skin-or dry benen-the mandrelself-supporting andto eliminate all` tendency to flow,- but should vnotcompletelyadry.vtheirubber, since-successivelayers vof rubbendonotalways adhere satisfactorily to dry late'xrubber.l The-dryingr-oi thetubes is comdryi;1r.ag;is usuellyzmost quickly-accomplishedif thehjumidityfof;theiair-'isfmaintained comparatively irubberA-whichfimpedes' the diiusion ofV moisture ''mandrel'fon form'y inthe `manner` described` and claimed@ in .the co-pending f application ofZim- '.'merli and: Semon,. Serial No. .310,434,1.led October 4, 1928which has become Patent 1,841,076. In this case it Will not benecessaryto dry the coating duringdep.osition sincethe .rubber-iisvrendered self-supporting by the coagulation.

' The latex which is employed may be the ordinary latex '-of commerce,that is, the ammoniapreserved latex derived from the Hevea brasiliensz'stree, orvit'may-v be the latex of other rubber trees, oreven of.gutta-percha or balata. It may be an artificial latex such as thatprepared by dispersingeohdrubber, rubber-like substances, or rubberderivatives in Water, or may consist ofl mixtures of 'any such naturalor artificial latices. Thelatex may contain pigments, fillers, coloringmatter, softeners, vulcanizing agents, accelerators of vulcanization',etc., such substances'. preferably being dissolved or nely dispersedin.an

alkaline solution and intimately admixed with the latex priorto thespraying operation;l If desired, the latex may even vloe-'vulcanizedwhile in` 95.,

`tion during drying. The latex is' preferablyof .sucha concentrationthat itisy sufli'ciently. fluid to be sprayed readily, but .does not.contain.=un-@I130 necessarilyl large proportions of Water which Wouldprolong the drying. A latex composition which is particularly valuablefor the production of inner tubes for automobilevtires yis prepared,for-example, by mixing the quantity of ammonia-i515 preserved naturalrubber latex containing parts by Weight of rubber With- 3 partsof zincoxide, 3 parts of sulphur, 0.3 parts otorganiciaccelerator and 1 part ofanti-oxidant; .The added solids are dispersed in Water, the dispersion-mixedill J with the latex and the concentration yof fthemixtureadjusted to about 50 %;'of .total solids. Rubber derived ,from thismixture maybe vulcanized in 20 minutes at 275 F.- Y

It is evident that the `machine, described 'abevei'4 5 is capable ofcontinuous-automatic. production of rubber tubes,requiringonlyzasupplyof latex in the tank 29, a supply ofuncoated'mandrels in the loading rack-.21,andthe removal of the coated'mandrels fromthe receiving rack 33; The#A subsequent treatment of thetubesdepends on the use to which they areto beput.- f If theyare tobecome inner tubes, for example, they are vulcanized,` stripped from themand-rel; provided with a'. valve stem, and spliced. If theyare tobeused for. stati-ener` bands, they are vulcanized and cut into bands ofthe proper Width;

A Vmachine'such'as that described above may `be employed for theproduction of tubes of almost any desired size or thickness byalteringv` the di-- mensions of the mandrels and-thedimensions and-operationof the machine.. Changes-lindir ameter are effected bychanging the. diameter of the mandrels. Changes in ylength* are effectedby changing the-length ofthe mandrels andthe: Widthl of `Vthe bank; of.sprayl nozzles,l Minor changes in 'thickness lareeffectedby changing theintensityof the spray,.or the rate of'movement of the conveyor, .and ifnecesary modifying .fthe temperature or'humidity of the drying-airac-`.cordingly.' Major changes in thickness 'are' effected vby changing thenumber of-,rowsofxspray nozzles in the spray bank.

It is vobviously possible` to adapt rthemethod and apparatus of Vthisinvention tothe continuous production of other shaped rubber articlesthan simple tubes.` VThe necessary modicationsoi?V the conveyor and oftheloadingandreceivingg racks, etc., to accommodate.the-:molds'for suchother4 articles, andfthe changes-in the.l disposition egg@ of the spraynozlzes in any given case will be obvious to those skilled in the art.

It is to be understood that the term latex, as herein employed, isintended to include natural latices of caoutchouc, gutta-percha, balata,etc., as well as artificial latices or aqueous emulsions of caoutchouc,gutta-percha, balata, reclaimed rubber, synthetic rubber, rubber isomersand like products, whether or not admixed with vulcanizing agents,pigments, fillers, etc., or previously purified, concentrated,vulcanized or otherwise treated.

Inasmuch as numerous embodiments of this invention may be made withoutexceeding the scope thereof, it is not intended to limit this inventionto the specific embodiment hereinabove described except as indicated inthe appended claims. Y

I claim: Y

1. The method of manufacturing shaped rubber articles which comprisespassing a continuous succession of forms past a group of spray nozzles,and spraying a plurality of coats of latex thereon, each coat beingpartially dried prior to the application of the subsequent coat.

2. The method of manufacturing rubber tubes which comprises passing acontinuous succession 1 of rotating cylindrical mandrels past a group ofspray nozzles, and spraying a plurality of coats of latex thereon, eachcoat being partially dried prior to the application of the subsequentcoat.

3. lIn a machine for the continuous manufacture of shaped rubberarticles, the combination of a series of forms, means for moving theforms in continuous succession in a predetermined path, means adjacentto the said path adapted lto spray successive coats of latex on theforms, and means adapted to dry the latex partially during the sprayingoperation and subsequently to complete the drying.

4. A machine for the continuous manufacture of rubber tubes comprising aseries of cylindrical mandrels, means for moving the mandrels incontinuous succession in a predetermined path, means for rotating themandrels, a' group of spray nozzles adapted to spray successive coats oflatex on the surface of the mandrels, and a dryer adapted to dry thelatex partially during the spraying operation and subsequently tocomplete the drying.

5. A machine for the continuous manufacture of rubber tubes comprising aseries of cylindrical mandrels, a conveyor adapted to carrya continuoussuccession of the mandrels, means for rotating the mandrels, a pluralityof groups of spray nozzles adapted to spray successive coats of latexuniformly over the length of the mandrels, and a dryer adapted to drythe latex partially during the spraying operation. Y

6. A machine for the continuous manufacture of rubber tubes comprising atunnel type dryer, an endless chain conveyor passing therethrough, aseries of cylindrical mandrels carried by the conveyor, means fordelivering the mandrels to the conveyor at onepoint in its path andremoving the mandrels at another point, means for rotating the mandrels,and a group of spray nozzles located within the confines of the dryerand adapted to spraylatex onthe surface of the mandrels.

7. A machine for the continuous manufacture of rubber tubes comprising aplurality of cylindrical mandrels terminating in supporting axles ofrelatively small diameter, a tunnel type dryer,

a pair of horizontal rails therein, said rails being adapted to receivethe supporting axles of the mandrels, means for causing the mandrels toroll slowlyv alongthe railsfand a group of spray nozzles within thedryer adapted to spray latex on the surface ofv the mandrels.

8. A machine' for the continuous manufacture of rubbertubesV comprising1a plurality of cylindrical mandrels terminating Vin supporting axles ofrelatively small diameter, a tunnel type dryer, a pair of horizontalrails therein, said rails being adapted to receive the supporting axlesof the mandrels,` means for causing the mandrels to roll slowly alongthe rails, and a plurality of groups of spray nozzles within the dryeradapted to spray successive coats of latex on thesurface of themandrels. v

9. Atmachine for the continuous manufacture of rubber tubes comprising aplurality of cylindrical mandrels terminating'in supporting axles ofrelativelyv small diameter, a tunnel type dryer,

ico

plying a continuous succession of closely spaced;

mandrels to the rails, means for causing the mandrels to roll slowlyalong the-rails, a plurality of groups of spray nozzles within the dryeradapted to spray successive coats of latex on the surface of themandrels, and means for receiving the coated mandrels. v

10. The method of manufacturing shaped rubber articles which comprisesrepeatedly applying a film of latex to the surface of a form, dryingeach film just enough to render it self-supporting before applying thesucceeding coating, and finally completing the drying of the shapedarticle on the form.

11. The method of manufacturing shaped rubber articles which comprisesrepeatedly applying a lm o f latex to the surface of a form, rotatingthe form to maintain a uniform distribution of the latex on the surfaceof the form, drying each film just enough to render it self-supportingVbefore applying the succeeding coating, and t finally completing thedrying of the shaped article on the form and vulcanizing the rubber.

12. The method of manufacturing shaped rubber articles which comprisessuccessively applycompleting theV drying of the-tubular rubberstructure. v o 14. The method of manufacturing rubber tubes whichcomprises moving a continuous series of rotating cylindrical mandrels ina direction perpendicular to their axes, applying a plurality of coatsof latex to each rotatingrmandrel in turn, partially vdrying each coatto render it selfsupporting `before the subsequent coat is applied,

tubular and finally completing the drying of the rubber structure. v

WALDO. L. SEMON.

